Brunson 771 - Page 25

21 Operation and Adjustment Manual
“leverage”iswhatgivesthetechniqueofautocollimation
itscapabilityforextremeaccuracy,butit’salsowhat
makesthereflectedreticleimage(atinfinity)morediffi‐
culttofind.

Onceyouhavefocusedthetelescopeatinfinity,proceed
tothenextstep.Butremember,don’tchangethetelescope
focuswhenperformingthenextstep.

4. Centertransiton“far”target.(Putreflectedreti‐
cleimageoveractualreticle.)Seeifyoucanlo‐
catethereticleimagethatisreflectedfromthe
“working”mirror.Usethehorizontalandverti‐
caltangentadjustmentscrewsonthetransitto
rotatethetelescopeslightlyintheelevation(up
anddown)orazimuth(leftandright)directions.
Watchforthereflectedimage.Performingthe
autoreflectionprocedureshouldhaveputyou
rightintheballpark,butsmalladjustmentsmay
stillbeneededtofindthereflectedreticleimage.
Onceyoufindit,we’lldefineitasthefartarget.Makean‐
gularadjustmentsasneededtoalignthereflectedreticle
imagedirectlyoverthetransit’sinternalreticle.

5. Centertransiton“near”target.Ifyouhadtomovesig‐
nificantlytofindthereflectedreticleimage,orifyou
foundonlyapartialorpoorqualityreflectedimage,you
probablyneedtoshiftthetransitlaterallyup/downor
right/leftinordertocenteritmorepreciselyonthework‐
ingmirror.Thistypeofproblemoftenindicatesthatyou
arelookingattheedgeofthemirrorratherthanafull‐on,
centrallyalignedview.Toachieveabetterresult,focus
thetelescopeagaintoviewthesurfaceoftheworking
mirror.Rememberthatinthebuck‐inprocess,thisisthe
neartarget.Makelateralshiftingadjustmentsasneeded,
usingthecross‐slideorprecisionlifttoalignthereticle
morenearlyinthecenter
ofthemirror.Thenfocusback
toinfinity(bywatchingforthereflectedreticleimage
nearinfinityfocususingeithertheworkingmirrororan‐
othermirrorheldagainsttheobjectiveendofthetele‐
scopeasdiscussedpreviously).

6. Repeatsteps4and5untilyouhaveagoodqualityre‐
flectedreticleimagewhichiscentereddirectlyoverthe
transit’sactualreticle.Rememberthatifyoustartthe
processwithanaccurateautoreflection,youwillhavean
importantadvantageinthisprocess.


Autocollimationusingthecross‐axistelescope

(76‐RHonly)


Rememberthatwhenfocused
atinfinity,onlythetransit’s
angularcontrolsproducevisi‐
bleresults.Lateralshiftsus‐
ingacross‐slideorprecision
liftwillnothelpyoualignto
thereflectedreticlewhenfo‐
cusedatinfinity.